In a vehicle such as a passenger car or a go-cart which has low vehicle height compared with vehicle width, the seat is relatively low so that the driver can sit in a low position to operate and drive the vehicle.
To the contrary, in a scooter-like vehicle provided with two steered wheels, the seat position is so high that the driver must sit on a seat high as an office chair to operate the vehicle. Since there is no extreme difference between the vehicle weight and the driver's weight, when the driver gets on, the center of gravity of the vehicle is positioned at a high point. Therefore, the stability of the vehicle must be controlled by the movement of the body of the driver.
In such vehicle, a bar type steering handle or a similar steering handle is chosen due to considerations of steerability and operatability of the vehicle. Because the center of gravity is high and the vehicle has no side wall to hold the driver's body against the lateral load at the time of turning, the driver must support his body with both arms by gripping the handle grips. Thus keeping feet on the floor, so that a foot operating member such as a treadle may be used, is difficult. Therefore, a steering member such as a steering bar, or a control wheel like that of an aircraft, which is easy to grip with both hands and is capable of being provided thereon with an operating mechanism, is used for easy operation.
However, as opposed to a conventional automobile provided with a steering wheel, the vehicle provided with this type of handle is difficult to operate in a wide operation range and the handle thereof is not capable of being steered by more than 90 degrees by the driver, because, at 90 degrees, the grip on one side of the handle contacts the side of the driver.
With such steering handle, if, on the one hand, the steering ratio is so predetermined as to be constant and low so that the vehicle can turn with a small radius, the movement of the vehicle body with the steering operation becomes so sensitive that the responses of the driver cannot follow it at the time of high speed running and the running stability is lowered. Therefore, such steering system is not desirable due to a lack of safety and running stability.
On the other hand, if the steering ratio is made high, the running stability increases but, if it is made too high, the vehicle body does not turn as expected in spite of proper steering operation when the vehicle turns a corner, such as at an intersection.
In view of the above, if the running stability is considered most important, the steering performance deteriorates so that the small radius turn cannot be made and the turn at a sharp angle becomes difficult. If only the steering performance is satisfied, the running stability is reduced so that the running becomes unstable and the vehicle becomes liable to tumble. Thus, the steering device of a vehicle provided with two steered wheels, having a high center of gravity and steered with a bar type steering or the like handle has been unsatisfactory in one of the above two areas, i.e., running stability or steering performance. Therefore, there is a need for an improvement in the steering system of such special vehicles.
Some of the structures for solving the above problems, wherein a steering bar or the like is connected to such steering gears as in a general vehicle, are complicated in construction; require a large mounting space; are difficult to mount on a simple light vehicle; and are impractical with respect to cost and space. Therefore, there is required a steering gear embodying an improved steering system which is simple in structure, has a high space utility and can be manufactured at low cost.
The present invention effectively solves the above mentioned problems.